1. Field of the Invention
The present invention relates to a semiconductor die package having an open cavity that exposes a semiconductor die held in the package to the environment and, more particularly, to an open-cavity semiconductor die package adapted to enable a person to place a finger tip on the semiconductor die.
2. Description of the Related Art
A semiconductor die or chip is an electrical component on which a microcircuit is built. The microcircuits can be interconnected together on the printed circuit board to form larger electrical circuits for use in radios, televisions, compact disk players, and computers, to name just a few. Because the semiconductor die is fragile, it is encased in a semiconductor die package to protect it from the environment. If one were to look inside an electronic device, such as a computer or a compact disk player, one would see one or more printed circuit boards on which semiconductor die packages are mounted and electrically interconnected.
The semiconductor die package includes a housing that holds the semiconductor die and conductive leads or pins that extend from the bottom or sides of the housing. The conductive leads are electrically connected to the semiconductor die within the housing. The outside ends of the leads are soldered to conductive paths on the printed circuit board. This secures the semiconductor die package to the printed circuit board and permits electrical signals to pass between the semiconductor die and other components on the printed circuit board.
In a conventional semiconductor die package, the housing encases the semiconductor die to prevent damage to the semiconductor die from exposure to the environment. The housing may be hermetically sealed, encased in plastic, or otherwise sealed against the environment. Some sealed packages can be opened, without damaging the semiconductor die or the wire bonding between the semiconductor die and the package leads, to allow reworking of the semiconductor die and the leads. These packages are re-sealed after reworking is completed. The process for resealing the package is complex and difficult to accomplish.
In some applications, it may be desirable to expose the semiconductor die to the environment. Some semiconductor dies are designed for use as sensors for sensing, for example, an environmental condition. As a result, at least a portion of the semiconductor dies must be exposed to the environment in order to perform sensing functions. For example, the semiconductor die may serve as a sensor for sensing a person's fingerprint for identification purposes. In this case, the person's finger must contact the semiconductor die to enable sensing. Conventional semiconductor die packages cannot be used for such applications because, as noted above, the packages are designed to encase and seal the semiconductor die to prevent exposure to the environment.